2.2 Measuring Earthquakes



Vocabulary


Focus: The point beneath Earth's surface where rock that is under stress breaks, triggering an earthquake.
Epicenter:The point on the surface directly above the focus.
P waves: earthquake waves that compress and expand the ground.
S waves: earthquake waves that vibrate from side to side as well as up and down.
Seismic waves: vibrations that travel through Earth carrying the energy released during an earthquake.
Surface waves: Produces the most severe ground movements.
Seismograph: Records ground movements caused by seismic waves as they move through the earth.
Magnitude: A measurement of earthquake strenghth based on seismic waves and movement along faults.
Mercalli scale: Was develpoed to rate eartquakes according to their intensity.
RItcher scale: A ranging of the siize of seismic waves as measured by a particular type oof mechanical seismograph.
Moment magnitude scale: a rating system that estimates thhe total energy released by an earthquake.



Outline


Seismic Waves

    • Seismic waves carry the energy of an earthquake away from the focus, through the Earth's interior, and across the surface.
    • There are three categories of seismic waves: P waves, S waves, and surface waves.
  • Primary Waves
  • Secondary Waves
  • Surface Waves

Detecting Seismic Waves


Measuring Earthquakes

  • The Mercalli Scale
  • The Richter Scale
  • The Moment Magnitude Scale

Locating the Epicenter


Diagram


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Locating the epicenter